1. Field of the Invention
The present invention relates to a forming method of a pattern film with a narrower width. The present invention further relates to a manufacturing method of a thin-film element having such a pattern film with a narrower width as a component, and more particularly, to a manufacturing method of a thin-film magnetic head used for magnetic recording. The present invention further relates to a thin-film magnetic head provided with a magnetic pole layer with such a narrower width.
2. Description of the Related Art
In recent years, with a demand for an increasingly large capacity and small size in magnetic disk drive apparatuses, further improvement of recording density is becoming indispensable. In order to realize a still higher recording density, it is indispensable to further narrow a track width of an upper magnetic pole layer of a head for longitudinal magnetic recording and a main magnetic pole layer of a head for perpendicular magnetic recording. Various experiments and development have been carried forward in pursuit for a forming method of the upper magnetic pole layer or the main magnetic pole layer capable of meeting such demands.
For example, Japanese Patent Publication No. 10-241125A and Japanese Patent Publication No. 2002-324304A describes a method of forming an upper magnetic film on a lower magnetic film and a gap film, by using a frame plating method, performing a dry etching method with this upper magnetic film as a mask, and forming an upper/lower magnetic film and a gap film having a predetermined width in a track width direction (hereinafter abbreviated as a “track width”). Here, Japanese Patent Publication No. 10-241125A includes a description that the track width is generally determined by a frame interval and an excellent manufacturing of a track width of up to 0.5 μm has been confirmed. Furthermore, Japanese Patent Publication No. 2002-324304A includes a further description that the track width is reduced to 0.5 μm or below by performing trimming using ion milling.
Furthermore, Japanese Patent Publication No. 2003-263705A discloses a method of providing a main magnetic pole of a magnetic head for perpendicular magnetic recording by forming a magnetic film using a frame plating method and then forming a reverse tapered shape (reverse trapezoidal shape) using ion milling. Furthermore, this Japanese Patent Publication No. 2003-263705A includes a description that a track width of 0.15 to 0.17 μm could be finally formed by ion milling.
As described above, according to the conventional forming method, the track width of the upper magnetic pole layer or the main magnetic pole layer is defined with a pattern interval provided by a photolithography method such as a resist frame in principle. This track width actually has a lower limit of approximately 0.2 μm due to a limitation of resolution of an exposure machine and resist normally in use. It is an actual situation that realizing a narrower width requires further etching with use of ion milling or the like as shown in Japanese Patent Publication No. 2003-263705A.
However, narrowing of the track width with use of etching also has a limitation and there may be also a problem with deterioration of a magnetic characteristic of the upper magnetic pole layer or the main magnetic pole layer due to etching.
In order to respond to a demand for a higher recording density, the track width of the upper magnetic pole layer or the main magnetic pole layer is required to be set to 0.15 μm or less. However, even when realizing the narrowing using an etching method such as ion milling, since an extremely fine pattern is already used before etching, it is extremely difficult to perform etching adequately while maintaining a desired shape. Furthermore, the magnetic characteristic deteriorates when the surface of the upper magnetic pole layer or the main magnetic pole layer receives impact from ions or the like.
Moreover, since the track width and the shape of the upper magnetic pole layer or the main magnetic pole layer is a very important parameter which determines intensity and distribution of the writing magnetic field (write field), they should be defined according to the intended design by using predetermined patterning without additional etching process as much as possible. Furthermore, even when ion beam etching or the like is used, the degree of etching should preferably be reduced to a minimum.